1. Field of the Invention
The present invention generally relates to electronic module repair and, more particularly, to a method for simultaneously removing a plurality of electronic devices or components (e.g., integrated circuit chips, capacitors, etc.) in a nondestructive process at very low cost.
2. Description of the Prior Art
There exists a need for a low-cost, high reliability process and apparatus for the removal of electronic devices and components from substrates, such as modules and printed circuit boards. The process and apparatus should remove devices and components nondestructively. Currently existing high-end processes which offer the desired reliability are quite costly and have relatively long turn around times. These processes are very limited to chip and substrate size and mass. In fact, removal of large chips planned on low-end modules cannot be performed with this technique. Cold processes utilized on low-end products are more risky to both the device and its carrier, often resulting in damage or destruction to either or both the device and its carrier.
Individual "hot" chip removal on high-end modules is accomplished by focusing an infrared lamp source through an aperture onto the back of the device and pulling a vacuum once the solder is molten. This tool and the process of using it is costly and time consuming but necessary to insure high reliability for high-end modules where both the chip and substrate complexity, as well as process sensitivity, is high. Also, as the silicon size continues to increase, focused localized heating techniques cause an extreme thermal gradient, not only in the x-y direction, but also through the z-axis of the chip where increased I/O result in a constant thermal drain from the device. These gradients are not controllable and can induce some defects, or heal other defects, making diagnostics impossible.
Several "cold" processes exist to remove devices on low-end products that are inherently cheaper; however, they run the risk of damage to both the chip and substrate. They include tensile pull, torque removal, and ultrasonic chip removal.
Previously, many chips have been placed on a single module. In some cases, each chip site can only be reworked four times, while each module can only be reflowed twelve times. Today, there are only about seven chips on a module, because the chips are larger. Reworking and reflowing limitations are not nearly as tough to work. The entire module may be heated.